﻿using System;
using System.IO;
using System.Collections.Generic;
using System.Text;

namespace Poi.NET.util
{
/**
 * representation of a short (16-bit) field at a fixed location within
 * a byte array
 *
 * @author Marc Johnson (mjohnson at apache dot org
 */
public class ShortField : FixedField
{
    private short     _value;
    private readonly int _offset;

    /**
     * construct the ShortField with its offset into its containing
     * byte array
     *
     * @param offset of the field within its byte array
     *
     * @exception ArrayIndexOutOfBoundsException if offset is negative
     */
    public ShortField(int offset)
    {
        if (offset < 0)
        {
            throw new IndexOutOfRangeException("Illegal offset: "
                                                     + offset);
        }
        _offset = offset;
    }

    /**
     * construct the ShortField with its offset into its containing
     * byte array and initialize its value
     *
     * @param offset of the field within its byte array
     * @param value the initial value
     *
     * @exception ArrayIndexOutOfBoundsException if offset is negative
     */
    public ShortField(int offset, short value) : this(offset)
    {
        set(value);
    }

    /**
     * Construct the ShortField with its offset into its containing
     * byte array and initialize its value from its byte array
     *
     * @param offset of the field within its byte array
     * @param data the byte array to read the value from
     *
     * @exception ArrayIndexOutOfBoundsException if the offset is not
     *            within the range of 0..(data.length - 1)
     */
    public ShortField(int offset, byte [] data) : this(offset)
    {
        readFromBytes(data);
    }

    /**
     * construct the ShortField with its offset into its containing
     * byte array, initialize its value, and write its value to its
     * byte array
     *
     * @param offset of the field within its byte array
     * @param value the initial value
     * @param data the byte array to write the value to
     *
     * @exception ArrayIndexOutOfBoundsException if offset is negative
     */
    public ShortField(int offset, short value, byte[] data) : this(offset)
    {
        set(value, data);
    }

    /**
     * get the ShortField's current value
     *
     * @return current value
     */
    public short get()
    {
        return _value;
    }

    /**
     * set the ShortField's current value
     *
     * @param value to be set
     */
    public void set(short value)
    {
        _value = value;
    }

    /**
     * set the ShortField's current value and write it to a byte array
     *
     * @param value to be set
     * @param data the byte array to write the value to
     *
     * @exception ArrayIndexOutOfBoundsException if the offset is out
     *            of range
     */
    public void set(short value, byte[] data)
    {
        _value = value;
        writeToBytes(data);
    }

    /* ********** START implementation of FixedField ********** */

    /**
     * set the value from its offset into an array of bytes
     *
     * @param data the byte array from which the value is to be read
     *
     * @exception ArrayIndexOutOfBoundsException if the offset is out
     *            of range
     */
    public void readFromBytes(byte[] data)
    {
        _value = LittleEndian.getShort(data, _offset);
    }

    /**
     * set the value from an InputStream
     *
     * @param stream the InputStream from which the value is to be
     *               read
     *
     * @exception BufferUnderrunException if there is not enough data
     *            available from the InputStream
     * @exception IOException if an IOException is thrown from reading
     *            the InputStream
     */
    public void readFromStream(StreamReader stream)
    {
        _value = LittleEndian.readShort(stream);
    }

    /**
     * write the value out to an array of bytes at the appropriate
     * offset
     *
     * @param data the array of bytes to which the value is to be
     *             written
     *
     * @exception ArrayIndexOutOfBoundsException if the offset is out
     *            of range
     */
    public void writeToBytes(byte[] data)
    {
        LittleEndian.putShort(data, _offset, _value);
    }

    /**
     * return the value as a String
     *
     * @return the value as a String
     */
    public String toString()
    {
        return _value.ToString();
    }

    /* **********  END  implementation of FixedField ********** */
}   // end public class ShortField

}
